and paren around -1; the canonical will make things look nicer in general,
too:
sp.Eq(*[(-1)**i*a for i, a in enumerate(reversed((ht * _lhs - ht *
_rhs).expand().as_independent(rho1, as_Add=True)))]).canonical
On Monday, May 8, 2017 at 12:04:29 PM UTC-5, Chris Smith wrote:
> with the closing paren!
>
>
> sp.Eq(*[-1**i*a for i, a in enumerate(reversed((ht * _lhs - ht *
> _rhs).expand().as_independent(rho1, as_Add=True)))])
>
>
> On Monday, May 8, 2017 at 12:02:35 PM UTC-5, Chris Smith wrote:
>
>> Not that I can think of. Good catch on the minus sign. And use the
>> `as_Add` flag unless you are positive that the expression you are working
>> with is always an Add. Does this work:
>>
>> sp.Eq(*[-1**i*a for i, a in enumerate(reversed((ht * _lhs - ht *
>> _rhs).expand().as_independent(rho1, as_Add=True)))]
>>
>> On Saturday, May 6, 2017 at 3:24:24 PM UTC-5, Jonathan Essen wrote:
>>
>>> Thank you for the reply, but I noticed that the new right hand side is
>>> off by an overall minus sign! I fixed it using:
>>>
>>> tmp = (ht * _lhs - ht * _rhs).expand().as_independent(rho1)
>>> sp.Eq(tmp[1], rhs=-tmp[0])
>>>
>>> Is there was a cleaner way to do this?
>>>
>>>
>>>
>>> On Thursday, May 4, 2017 at 8:21:44 AM UTC-7, Chris Smith wrote:
>>>>
>>>> Given Eq(L, R) where L and R are the left and right hand sides of the
>>>> equation, try: `Eq(*list(reversed((L - R).expand().as_indepedent(foo,
>>>> as_Add=True))))` where foo is the variable of interest to get the new
>>>> equation.
>>>>
>>>> On Tuesday, April 25, 2017 at 2:35:10 PM UTC-5, Jonathan Essen wrote:
>>>>>
>>>>> I am attempting to use sympy to generate an implicit scheme for the
>>>>> heat equation. With the Crank-Nicolson time discretization I have
>>>>> equation
>>>>> 1 (attached).
>>>>>
>>>>> Is there any way to isolate all occurrences of $\rho^{n+1}$ (along
>>>>> with its derivatves) to the lefthand side, as in equation 2 (attached).
>>>>>
>>>>> I would be very interested to know! Apparently it has something to do
>>>>> with the collect function.
>>>>>
>>>>> Best,
>>>>> Jonathan
>>>>>
>>>>
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